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2012

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Articles 121 - 150 of 352

Full-Text Articles in Astrophysics and Astronomy

The Hd 192263 System: Planetary Orbital Period And Stellar Variability Disentangled, D. Dragomir, S. R. Kane, G. W. Henry, D. R. Ciardi, D. A. Fischer, A. W. Howard, Eric L.N. Jensen, G. Laughlin, S. Mahadevan, J. M. Matthews, G. Pilyavsky, K. Von Braun, S. X. Wang, J. T. Wright Jul 2012

The Hd 192263 System: Planetary Orbital Period And Stellar Variability Disentangled, D. Dragomir, S. R. Kane, G. W. Henry, D. R. Ciardi, D. A. Fischer, A. W. Howard, Eric L.N. Jensen, G. Laughlin, S. Mahadevan, J. M. Matthews, G. Pilyavsky, K. Von Braun, S. X. Wang, J. T. Wright

Physics & Astronomy Faculty Works

As part of the Transit Ephemeris Refinement and Monitoring Survey, we present new radial velocities and photometry of the HD 192263 system. Our analysis of the already available Keck-HIRES and CORALIE radial velocity measurements together with the five new Keck measurements we report in this paper results in improved orbital parameters for the system. We derive constraints on the size and phase location of the transit window for HD 192263b, a Jupiter-mass planet with a period of 24.3587 +/- 0.0022 days. We use 10 years of Automated Photoelectric Telescope photometry to analyze the stellar variability and search for planetary transits. …

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Veritas Observations Of The Nova In V407 Cygni, P. T. Reynolds, Et. Al. Jul 2012

Veritas Observations Of The Nova In V407 Cygni, P. T. Reynolds, Et. Al.

Physical Sciences Publications

We report on very high energy (E > 100 GeV) gamma-ray observations of V407 Cygni, a symbiotic binary that underwent a nova outburst producing 0.1-10 GeV gamma rays during 2010 March 10-26. Observations were made with the Very Energetic Radiation Imaging Telescope Array System during 2010 March 19-26 at relatively large zenith angles due to the position of V407 Cyg. An improved reconstruction technique for large zenith angle observations is presented and used to analyze the data. We do not detect V407 Cygni and place a differential upper limit on the flux at 1.6 TeV of 2.3 × 10–12 erg cm–2 …

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Array-Based Characterization Of Military Jet Aircraft Noise, David William Krueger Jul 2012

Array-Based Characterization Of Military Jet Aircraft Noise, David William Krueger

Theses and Dissertations

Since the 1950s the jet aeroacoustics community has been involved in predicting and measuring the noise distribution in jets. In this work, cylindrical and planar Fourier near-field acoustical holography are used to investigate radiation from a full-scale, installed jet engine. Practical problems involving measurement aperture and the highly directional nature of the source are addressed. Insights from numerical simulations reveal usable reconstruction regions. A comparison of cylindrical and planar NAH for the respective measurement apertures shows cylindrical NAH outperforms planar NAH on reconstructions both towards and away from the source.

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Pt-Symmetric Talbot Effects, Hamidreza Ramezani, D. N. Christodoulides, V. Kovanis, I. Vitebskiy, Tsampikos Kottos Jul 2012

Pt-Symmetric Talbot Effects, Hamidreza Ramezani, D. N. Christodoulides, V. Kovanis, I. Vitebskiy, Tsampikos Kottos

Physics & Astronomy Faculty Publications

We show that complex PT-symmetric photonic lattices can lead to a new class of self-imaging Talbot effects. For this to occur, we find that the input field pattern has to respect specific periodicities dictated by the symmetries of the system. While at the spontaneous PT-symmetry breaking point the image revivals occur at Talbot lengths governed by the characteristics of the passive lattice, at the exact phase it depends on the gain and loss parameter, thus allowing one to control the imaging process. © 2012 American Physical Society.

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Deep Silicate Absorption Features In Compton-Thick Active Galactic Nuclei Predominantly Arise Due To Dust In The Host Galaxy, A. D. Goulding, D. M. Alexander, F. E. Bauer, W. R. Forman, R. C. Hickox Jul 2012

Deep Silicate Absorption Features In Compton-Thick Active Galactic Nuclei Predominantly Arise Due To Dust In The Host Galaxy, A. D. Goulding, D. M. Alexander, F. E. Bauer, W. R. Forman, R. C. Hickox

Dartmouth Scholarship

We explore the origin of mid-infrared (mid-IR) dust extinction in all 20 nearby (z < 0.05) bona fide Compton-thick (N H > 1.5 × 1024 cm–2) active galactic nuclei (AGNs) with hard energy (E > 10 keV) X-ray spectral measurements. We accurately measure the silicate absorption features at λ ~ 9.7 μm in archival low-resolution (R ~ 57-127) Spitzer Infrared Spectrograph spectroscopy, and show that only a minority (≈45%) of nearby Compton-thick AGNs have strong Si-absorption features (S 9.7 = ln (f int/f obs) 0.5) which would indicate significant dust attenuation. The majority (≈60%) are star …

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Absolute Properties Of The Eclipsing Binary Star V335 Serpentis, Claud H. Sandberg Lacy, Francis C. Fekel, Antonio Claret Jul 2012

Absolute Properties Of The Eclipsing Binary Star V335 Serpentis, Claud H. Sandberg Lacy, Francis C. Fekel, Antonio Claret

Information Systems and Engineering Management Research Publications

V335 Ser is now known to be an eccentric double-lined A1+A3 binary star with fairly deep (0.5 mag) partial eclipses. Previous studies of the system are improved with 7456 differential photometric observations from the URSA WebScope and 5666 from the NFO WebScope, and 67 high-resolution spectroscopic observations from the Tennessee State University 2 m automatic spectroscopic telescope. From dates of minima, the apsidal period is about 880 years. Accurate (better than 2%) masses and radii are determined from analysis of the two new light curves and the radial velocity curve. Theoretical models match the absolute properties of the stars at …

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Analog Feedback Control Of Broadband Fan Noise, Cole Victor Duke Jul 2012

Analog Feedback Control Of Broadband Fan Noise, Cole Victor Duke

Theses and Dissertations

Active noise control (ANC) has been implemented using analog filters to reduce broadband noise from a small axial cooling fan. Previous work successfully attenuated narrow-band, tonal portions of the noise using a digital controller. The practical performance limits of this system were reached and it was desirable to attenuate the noise further. Additional research, therefore, sought to attenuate broadband noise from the fan using a digital controller, but performance was limited by the group delay inherent in the digital signal processor (DSP). Current research attempts to further attenuate broadband noise and improve performance of the system by combining the tonal …

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A Proper Motion Study Of The Haro 6-10 Outflow: Evidence For A Subarcsecond Binary, Bruce Wilking, Kevin Marvel, Mark Claussen, Bradley Gerling, Alwyn Wootten, Erika Gibb Jul 2012

A Proper Motion Study Of The Haro 6-10 Outflow: Evidence For A Subarcsecond Binary, Bruce Wilking, Kevin Marvel, Mark Claussen, Bradley Gerling, Alwyn Wootten, Erika Gibb

Physics Faculty Works

We present single-dish and very long baseline interferometry observations of an outburst of water maser emission from the young binary system Haro 6-10. Haro 6-10 lies in the Taurus molecular cloud and contains a visible T Tauri star with an infrared companion 1farcs3 north. Using the Very Long Baseline Array, we obtained five observations spanning three months and derived absolute positions for 20 distinct maser spots. Three of the masers can be traced over three or more epochs, enabling us to extract absolute proper motions and tangential velocities. We deduce that the masers represent one side of a bipolar outflow …

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Discovery Of The Optical/Ultraviolet/Gamma-Ray Counterpart To The Eclipsing Millisecond Pulsar J1816+4510, D. L. Kaplan, Kevin Stovall, S. M. Ransom, M. S. R. Robers, R. Kotulla, Anne M. Archibald, C. M. Biwer, Anthony J. Ford, Fredrick Jenet Jul 2012

Discovery Of The Optical/Ultraviolet/Gamma-Ray Counterpart To The Eclipsing Millisecond Pulsar J1816+4510, D. L. Kaplan, Kevin Stovall, S. M. Ransom, M. S. R. Robers, R. Kotulla, Anne M. Archibald, C. M. Biwer, Anthony J. Ford, Fredrick Jenet

Physics & Astronomy Faculty Publications

The energetic, eclipsing millisecond pulsar J1816+4510 was recently discovered in a low-frequency radio survey with the Green Bank Telescope. With an orbital period of 8.7 hr and a minimum companion mass of 0.16 M☉, it appears to belong to an increasingly important class of pulsars that are ablating their low-mass companions. We report the discovery of the γ-ray counterpart to this pulsar and present a likely optical/ultraviolet counterpart as well. Using the radio ephemeris, we detect pulsations in the unclassified γ-ray source 2FGL J1816.5+4511, implying an efficiency of ∼25% in converting the pulsar's spin-down luminosity into γ-rays and adding PSR …

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Practical Methods For Continuous Gravitational Wave Detection Using Pulsar Timing Data, J. A. Ellis, F. A. Jenet, M. A. Mclaughlin Jul 2012

Practical Methods For Continuous Gravitational Wave Detection Using Pulsar Timing Data, J. A. Ellis, F. A. Jenet, M. A. Mclaughlin

Physics & Astronomy Faculty Publications

Gravitational waves (GWs) are tiny ripples in the fabric of space time predicted by Einstein's general relativity. Pulsar timing arrays (PTAs) are well poised to detect low-frequency (10-9-10-7 Hz) GWs in the near future. There has been a significant amount of research into the detection of a stochastic background of GWs from supermassive black hole binaries (SMBHBs). Recent work has shown that single continuous sources standing out above the background may be detectable by PTAs operating at a sensitivity sufficient to detect the stochastic background. The most likely sources of continuous GWs in the pulsar timing frequency band are extremely …

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Entropic Measure For Localized Energy Configurations: Kinks, Bounces, And Bubbles, Marcelo Gleiser, Nikitas Stamatopoulos Jul 2012

Entropic Measure For Localized Energy Configurations: Kinks, Bounces, And Bubbles, Marcelo Gleiser, Nikitas Stamatopoulos

Dartmouth Scholarship

No abstract provided.

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The Gas/Dust Ratio Of Circumstellar Disks: Testing Models Of Planetesimal Formation, David Horne, Erika Gibb, Terrence Rettig, Sean Brittain, David Tilley, Dinshaw Balsara Jul 2012

The Gas/Dust Ratio Of Circumstellar Disks: Testing Models Of Planetesimal Formation, David Horne, Erika Gibb, Terrence Rettig, Sean Brittain, David Tilley, Dinshaw Balsara

Physics Faculty Works

We present high-resolution, near-infrared NIRSPEC observations of CO absorption toward six class II T Tauri stars: AA Tau, DG Tau, IQ Tau, RY Tau, CW Tau, and Haro 6-5b. 12CO overtone absorption lines originating from the circumstellar disk of each object were used to calculate line-of-sight gas column densities toward each source. We measured the gas/dust ratio as a function of disk inclination, utilizing measured visual extinctions and inclinations for each star. The majority of our sources show further evidence for a correlation between the gas/dust column density ratio and disk inclination similar to that found by Rettig et al.

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Elastic Properties Of The Zintl Ferromagnet Yb14mnsb11, Sriparna Bhattacharya, D C. Marinescu, James R. Morris, Ivan A. Sergienko, Brian Sales, David Madrus, Veerle Keppens Jul 2012

Elastic Properties Of The Zintl Ferromagnet Yb14mnsb11, Sriparna Bhattacharya, D C. Marinescu, James R. Morris, Ivan A. Sergienko, Brian Sales, David Madrus, Veerle Keppens

Publications

We report measurements of the elastic moduli as a function of temperature (5–300) K and magnetic field (0–2 T) for the Zintl ferromagnet Yb14MnSb11, which is believed to be a rare example of an underscreened Kondo lattice. The elastic moduli measured below the Curie temperature in this complex ferromagnet exhibit unusual lattice stiffening that is independent of the magnetic field and can be adequately modeled using the Landau theory.

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The Hd 192263 System: Planetary Orbital Period And Stellar Variability Disentangled, Diana Dragomir, Stephen R. Kane, Gregory W. Henry, David R. Ciardi, Debra A. Fischer, Andrew W. Howard, Eric L. N. Jensen, Gregory Laughlin, Suvrath Mahadevan, Jaymie M. Matthews, Genady Pilyavsky, Kaspar Von Braun, Sharon X. Wang, Jason T. Wright Jul 2012

The Hd 192263 System: Planetary Orbital Period And Stellar Variability Disentangled, Diana Dragomir, Stephen R. Kane, Gregory W. Henry, David R. Ciardi, Debra A. Fischer, Andrew W. Howard, Eric L. N. Jensen, Gregory Laughlin, Suvrath Mahadevan, Jaymie M. Matthews, Genady Pilyavsky, Kaspar Von Braun, Sharon X. Wang, Jason T. Wright

Information Systems and Engineering Management Research Publications

As part of the Transit Ephemeris Refinement and Monitoring Survey, we present new radial velocities and photometry of the HD 192263 system. Our analysis of the already available Keck-HIRES and CORALIE radial velocity measurements together with the five new Keck measurements we report in this paper results in improved orbital parameters for the system. We derive constraints on the size and phase location of the transit window for HD 192263b, a Jupiter-mass planet with a period of 24.3587 ± 0.0022 days. We use 10 years of Automated Photoelectric Telescope photometry to analyze the stellar variability and search for planetary transits. …

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Herschel/Pacs Observations Of Young Sources In Taurus: The Far-Infrared Counterpart Of Optical Jets, L Podio, I Kamp, D Flower, C Howard, G Sandell, A Mora, G Aresu, Sean D. Brittain, W.R.F. Dent, C Pinte, G J. White Jul 2012

Herschel/Pacs Observations Of Young Sources In Taurus: The Far-Infrared Counterpart Of Optical Jets, L Podio, I Kamp, D Flower, C Howard, G Sandell, A Mora, G Aresu, Sean D. Brittain, W.R.F. Dent, C Pinte, G J. White

Publications

Context. Observations of the atomic and molecular line emission associated with jets and outflows emitted by young stellar objects provide sensitive diagnostics of the excitation conditions, and can be used to trace the various evolutionary stages they pass through as they evolve to become main sequence stars. Aims. To understand the relevance of atomic and molecular cooling in shocks, and how accretion and ejection efficiency evolves with the evolutionary state of the sources, we will study the far-infrared counterparts of bright optical jets associated with Class I and II sources in Taurus (T Tau, DG Tau A, DG Tau B, …

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On The Determination Of The Spin Of The Black Hole In Cyg X-1 From X-Ray Reflection Spectra, A. C. Fabian, D. R. Wilkins, J. M. Miller, R. C. Reis, C. S. Reynolds, E. M. Cackett, M. A. Nowak, G. G. Pooley, K. Pottschmidt, J. S. Sanders, R. R. Ross, J. Wilms Jul 2012

On The Determination Of The Spin Of The Black Hole In Cyg X-1 From X-Ray Reflection Spectra, A. C. Fabian, D. R. Wilkins, J. M. Miller, R. C. Reis, C. S. Reynolds, E. M. Cackett, M. A. Nowak, G. G. Pooley, K. Pottschmidt, J. S. Sanders, R. R. Ross, J. Wilms

Physics and Astronomy Faculty Research Publications

The spin of Cygnus X-1 is measured by fitting reflection models to Suzaku data covering the energy band 0.9-400 keV. The inner radius of the accretion disc is found to lie within 2 gravitational radii (rg=GM/c2), and a value of ? is obtained for the dimensionless black hole spin. This agrees with recent measurements using the continuum fitting method by Gou et al. and of the broad iron line by Duro et al. The disc inclination is measured at ?, which is consistent with the recent optical measurement of the binary system inclination by Orosz et …

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Simulated Lsst Survey Of Rr Lyrae Stars Throughout The Local Group, Hakeem M. Oluseyi, Christopher Culliton, Muhammad Furqan, Keri L. Hoadley, Paul Regencia, Akeem J. Wells Jul 2012

Simulated Lsst Survey Of Rr Lyrae Stars Throughout The Local Group, Hakeem M. Oluseyi, Christopher Culliton, Muhammad Furqan, Keri L. Hoadley, Paul Regencia, Akeem J. Wells

Aerospace, Physics, and Space Science Faculty Publications

We report on a study to determine the efficiency of the Large Synoptic Survey Telescope (LSST) to recover the periods, brightnesses, and shapes of RR Lyrae stars’ light curves in the volume extending to heliocentric distances of 1.5 Mpc. We place the smoothed light curves of 30 type ab and 10 type c RR Lyrae stars in 1007 fields across the sky, each of which represents a different realization of the LSST sampling cadences, and that sample five particular observing modes. A light curve simulation tool was used to sample the idealized RR Lyrae stars’ light curves, returning each as …

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Fourier Transform Infrared Spectroscopy And Wide-Angle X-Ray Scattering: Investigations On Polypropylene-Vapor-Grown Carbon Nanofiber Composites, Mircea Chipara, John Hamilton, Alin Cristian Chipara, Tom George, Dorina M. Chipara, Elamin Ibrahim, Karen Lozano, David J. Sellmyer Jul 2012

Fourier Transform Infrared Spectroscopy And Wide-Angle X-Ray Scattering: Investigations On Polypropylene-Vapor-Grown Carbon Nanofiber Composites, Mircea Chipara, John Hamilton, Alin Cristian Chipara, Tom George, Dorina M. Chipara, Elamin Ibrahim, Karen Lozano, David J. Sellmyer

Physics & Astronomy Faculty Publications

Fourier transform infrared (FTIR) spectroscopy and wide-angle X-ray scattering (WAXS) investigations of isotactic polypropylene (iPP)-vapor-grown carbon nanofiber (VGCNF) composites containing various amounts of VGCNFs ranging between 0 and 20 wt %. are reported. The FTIR investigations were focused on the regularity bands of iPP. The FTIR data indicated a drop in the isotacticity index as the concentration of nanofibers was increased; this suggested a decrease in the crystallinity. WAXS measurements revealed a dominating α 1 phase, with a small admixture of γ phase or mesophase. The loading of the polymeric matrix with carbon nanofibers (CNFs) did not induce significant changes …

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Evolution In The Dust Lane Fraction Of Edge-On L*V Spiral Galaxies Since Z = 0.8., Benne W. Holwerda, J. J. Dalcanton, D. Radburn-Smith, R. S. De Jong, P. Guhathakurta, A. Koekemoer, R. J. Allen, T. Boker Jul 2012

Evolution In The Dust Lane Fraction Of Edge-On L*V Spiral Galaxies Since Z = 0.8., Benne W. Holwerda, J. J. Dalcanton, D. Radburn-Smith, R. S. De Jong, P. Guhathakurta, A. Koekemoer, R. J. Allen, T. Boker

Faculty and Staff Scholarship

The presence of a well-defined and narrow dust lane in an edge-on spiral galaxy is the observational signature of a thin and dense molecular disk, in which gravitational collapse has overcome turbulence. Using a sample of galaxies out to z ∼ 1 extracted from the COSMOS survey, we identify the fraction of massive (L∗ V ) disks that display a dust lane. Our goal is to explore the evolution in the stability of the molecular interstellar medium (ISM) disks in spiral galaxies over a cosmic timescale. We check the reliability of our morphological classifications against changes in rest-frame wavelength, resolution, …

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Outer-Disk Populations In Ngc 7793 : Evidence For Stellar Radial Migration., David J. Radburn-Smith, Rok Roskar, Victor P. Debattista, Julianne J. Dalcanton, David Streich, Roelof S. De Jong, Marija Vlajic, Benne W. Holwerda, Chris W. Purcell, Andrew E. Dolphin, Daniel B. Zucker Jul 2012

Outer-Disk Populations In Ngc 7793 : Evidence For Stellar Radial Migration., David J. Radburn-Smith, Rok Roskar, Victor P. Debattista, Julianne J. Dalcanton, David Streich, Roelof S. De Jong, Marija Vlajic, Benne W. Holwerda, Chris W. Purcell, Andrew E. Dolphin, Daniel B. Zucker

Faculty and Staff Scholarship

We analyzed the radial surface brightness profile of the spiral galaxy NGC 7793 using HST/ACS images from the GHOSTS survey and a new HST/WFC3 image across the disk break. We used the photometry of resolved stars to select distinct populations covering a wide range of stellar ages. We found breaks in the radial profiles of all stellar populations at 280 (∼5.1 kpc). Beyond this disk break, the profiles become steeper for younger populations. This same trend is seen in numerical simulations where the outer disk is formed almost entirely by radial migration. We also found that the older stars of …

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3.6 And 4.5 Μm Phase Curves And Evidence For Non-Equilibrium Chemistry In The Atmosphere Of Extrasolar Planet Hd 189733b, Heather A. Knutson, Nikole K. Lewis, Jonathan J. Fortney, Adam Burrows, Adam P. Showman, Nicolas B. Cowan, Eric Agol, Suzanne Aigrain, David Charbonneau, Drake Deming, Jean-Michel Désert, Gregory W. Henry, Jonathan Langton, Gregory Laughlin Jun 2012

3.6 And 4.5 Μm Phase Curves And Evidence For Non-Equilibrium Chemistry In The Atmosphere Of Extrasolar Planet Hd 189733b, Heather A. Knutson, Nikole K. Lewis, Jonathan J. Fortney, Adam Burrows, Adam P. Showman, Nicolas B. Cowan, Eric Agol, Suzanne Aigrain, David Charbonneau, Drake Deming, Jean-Michel Désert, Gregory W. Henry, Jonathan Langton, Gregory Laughlin

Information Systems and Engineering Management Research Publications

We present new, full-orbit observations of the infrared phase variations of the canonical hot Jupiter HD 189733b obtained in the 3.6 and 4.5 μm bands using the Spitzer Space Telescope. When combined with previous phase curve observations at 8.0 and 24 μm, these data allow us to characterize the exoplanet's emission spectrum as a function of planetary longitude and to search for local variations in its vertical thermal profile and atmospheric composition. We utilize an improved method for removing the effects of intrapixel sensitivity variations and robustly extracting phase curve signals from these data, and we calculate our best-fit parameters …

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Bypassing The Bandwidth Theorem With Pt Symmetry, Hamidreza Ramezani, J. Schindler, F. M. Ellis, Uwe Günther, Tsampikos Kottos Jun 2012

Bypassing The Bandwidth Theorem With Pt Symmetry, Hamidreza Ramezani, J. Schindler, F. M. Ellis, Uwe Günther, Tsampikos Kottos

Physics & Astronomy Faculty Publications

The beat time τ fpt associated with the energy transfer between two coupled oscillators is dictated by the bandwidth theorem which sets a lower bound τ fpt∼1/δω. We show, both experimentally and theoretically, that two coupled active LRC electrical oscillators with parity-time (PT) symmetry bypass the lower bound imposed by the bandwidth theorem, reducing the beat time to zero while retaining a real valued spectrum and fixed eigenfrequency difference δω. Our results foster design strategies which lead to (stable) pseudounitary wave evolution, and may allow for ultrafast computation, telecommunication, and signal processing. © 2012 American Physical Society.

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Analysis Of The Early-Time Optical Spectra Of Sn 2011fe In M101, J. T. Parrent, D. A. Howell, B. Friesen, R. C. Thomas Jun 2012

Analysis Of The Early-Time Optical Spectra Of Sn 2011fe In M101, J. T. Parrent, D. A. Howell, B. Friesen, R. C. Thomas

Dartmouth Scholarship

The nearby Type Ia supernova SN 2011fe in M101 (cz=241 km s^-1) provides a unique opportunity to study the early evolution of a "normal" Type Ia supernova, its compositional structure, and its elusive progenitor system. We present 18 high signal-to-noise spectra of SN 2011fe during its first month beginning 1.2 days post-explosion and with an average cadence of 1.8 days. This gives a clear picture of how various line-forming species are distributed within the outer layers of the ejecta, including that of unburned material (C+O). We follow the evolution of C II absorption features until they diminish near maximum light, …

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All-Sky Search For Gravitational-Wave Bursts In The Second Joint Ligo-Virgo Run, J. Abadie, B. P. Abbott, R. Abbott, Matthew Benacquista, Teviet Creighton, Mario C. Diaz, Soumya Mohanty, Volker Quetschke, Malik Rakhmanov, Joseph D. Romano Jun 2012

All-Sky Search For Gravitational-Wave Bursts In The Second Joint Ligo-Virgo Run, J. Abadie, B. P. Abbott, R. Abbott, Matthew Benacquista, Teviet Creighton, Mario C. Diaz, Soumya Mohanty, Volker Quetschke, Malik Rakhmanov, Joseph D. Romano

Physics & Astronomy Faculty Publications

We present results from a search for gravitational-wave bursts in the data collected by the LIGO and Virgo detectors between July 7, 2009 and October 20, 2010: data are analyzed when at least two of the three LIGO-Virgo detectors are in coincident operation, with a total observation time of 207 days. The analysis searches for transients of duration -1s over the frequency band 64-5000 Hz, without other assumptions on the signal waveform, polarization, direction or occurrence time. All identified events are consistent with the expected accidental background. We set frequentist upper limits on the rate of gravitational-wave bursts by combining …

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Findchirp: An Algorithm For Detection Of Gravitational Waves From Inspiraling Compact Binaries, Bruce Allen, Warren G. Anderson, Patrick R. Brady, Duncan A. Brown, Jolien D E Creighton Jun 2012

Findchirp: An Algorithm For Detection Of Gravitational Waves From Inspiraling Compact Binaries, Bruce Allen, Warren G. Anderson, Patrick R. Brady, Duncan A. Brown, Jolien D E Creighton

Physics - All Scholarship

Matched-filter searches for gravitational waves from coalescing compact binaries by the LIGO Scientific Collaboration use the FINDCHIRP algorithm: an implementation of the optimal filter with innovations to account for unknown signal parameters and to improve performance on detector data that has nonstationary and non-Gaussian artifacts. We provide details on the FINDCHIRP algorithm as used in the search for subsolar mass binaries, binary neutron stars, neutron star-black hole binaries, and binary black holes.

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The Hidden “Agn Main Sequence”: Evidence For A Universal Black Hole Accretion To Star Formation Rate Ratio Since Z ∼ 2 Producing An M Bh - M * Relation, J. R. Mullaney, E. Daddi, M. Béthermin, D. Elbaz, S. Juneau, M. Pannella, M. T. Sargent, D. M. Alexander, R. C. Hickox Jun 2012

The Hidden “Agn Main Sequence”: Evidence For A Universal Black Hole Accretion To Star Formation Rate Ratio Since Z ∼ 2 Producing An M Bh - M * Relation, J. R. Mullaney, E. Daddi, M. Béthermin, D. Elbaz, S. Juneau, M. Pannella, M. T. Sargent, D. M. Alexander, R. C. Hickox

Dartmouth Scholarship

Using X-ray stacking analyses we estimate the average amounts of supermassive black hole (SMBH) growth taking place in star-forming galaxies at z ~ 1 and z ~ 2 as a function of galaxy stellar mass (M *). We find that the average SMBH growth rate follows remarkably similar trends with M * and redshift as the average star formation rates (SFRs) of their host galaxies (i.e., \dot{M}_BH vprop M * 0.86 ± 0.39 for the z ~ 1 sample and \dot{M}_BH vprop M * 1.05 ± 0.36 for the z ~ 2 sample). It follows that the ratio of …

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Discovery Of Tev Gamma-Ray Emission Toward Supernova Remnant Snr G78.2+2.1, P. T. Reynolds, Et. Al. Jun 2012

Discovery Of Tev Gamma-Ray Emission Toward Supernova Remnant Snr G78.2+2.1, P. T. Reynolds, Et. Al.

Physical Sciences Publications

We report the discovery of an unidentified, extended source of very-high-energy gamma-ray emission, VER J2019+407, within the radio shell of the supernova remnant SNR G78.2+2.1, using 21.4 hr of data taken by the VERITAS gamma-ray observatory in 2009. These data confirm the preliminary indications of gamma-ray emission previously seen in a two-year (2007-2009) blind survey of the Cygnus region by VERITAS. VER J2019+407, which is detected at a post-trials significance of 7.5 standard deviations in the 2009 data, is localized to the northwestern rim of the remnant in a region of enhanced radio and X-ray emission. It has an intrinsic …

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Flux And Photon Spectral Index Distributions Of Fermi-Lat Blazars And Contribution To The Extragalactic Gamma-Ray Background, Jack Singal, V. Petrosian, M. Ajello Jun 2012

Flux And Photon Spectral Index Distributions Of Fermi-Lat Blazars And Contribution To The Extragalactic Gamma-Ray Background, Jack Singal, V. Petrosian, M. Ajello

Physics Faculty Publications

We present a determination of the distributions of the photon spectral index and gamma-ray flux—the so-called log N–log S relation—for the 352 blazars detected with a greater than approximately 7σ detection threshold and located above ±20◦ Galactic latitude by the Large Area Telescope of the Fermi Gamma-ray Space Telescope in its first year catalog. Because the flux detection threshold depends on the photon index, the observed raw distributions do not provide the true log N–log S counts or the true distribution of the photon index. We use the non-parametric methods developed by Efron and Petrosian to reconstruct the intrinsic distributions …

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Observed Seasonal Variations In Exospheric Effective Temperatures, E. J. Mierkiewicz, F. L. Roesler, S. M. Nossal Jun 2012

Observed Seasonal Variations In Exospheric Effective Temperatures, E. J. Mierkiewicz, F. L. Roesler, S. M. Nossal

Publications

High spectral resolution line profile observations indicate a reproducible semi-annual variation in the geocoronal hydrogen Balmer α effective temperature. These observations were made between 08 January 2000 and 21 November 2001 from Pine Bluff Observatory (WI) with a second generation double etalon Fabry-Perot annular summing spectrometer operating at a resolving power of 80,000. This data set spans sixty-four nights of observations (1404 spectra in total) over 20 dark-moon periods. A two cluster Gaussian model fitting procedure is used to determine Doppler line widths, accounting for fine structure contributions to the line, including those due to cascade; cascade contributions at Balmer …

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Detecting Gravitational Wave Memory With Pulsar Timing, J. M. Cordes, F. A. Jenet Jun 2012

Detecting Gravitational Wave Memory With Pulsar Timing, J. M. Cordes, F. A. Jenet

Physics & Astronomy Faculty Publications

We compare the detectability of gravitational bursts passing through the solar system with those passing near each millisecond pulsar in an N-pulsar timing array. The sensitivity to Earth-passing bursts can exploit the correlation expected in pulse arrival times while pulsar-passing bursts, though uncorrelated between objects, provide an N-fold increase in overall time baseline that can compensate for the lower sensitivity. Bursts with memory from mergers of supermassive black holes produce step functions in apparent spin frequency that are the easiest to detect in pulsar timing. We show that the burst rate and amplitude distribution, while strongly dependent on inadequately known …

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